Shorting device for secondary terminals of current transformers



Jan 31, 1967 v R. 1.. DAVIS, JR 3,301,987

SHORTING DE E FO E DAR ERMINALS OF RENT A ORM Filed Aug. I l, 1965 2Sheets-Sheet 1 [7216/2753 A f 362/6/ A P0129, /f.

R. DAVIS, JR 3,301,987 VICE FOR ECONDARY TERMINALS CURRENT TRANSFORMERSJan. 31, 1967 SHORTING DE 2 Sheets-Sheet 2 Filed Aug. 51, 1955 UnitedStates Patent 3,301,987 SHORTING DEVICE FOR SECONDARY TERMI- NALS OFCURRENT TRANSFORMERS Reuel L. Davis, Jr., Dover, N.H., assignor toGeneral Electric Company, a corporation of New York Filed Aug. 31, 1965,Ser. No. 484,037 3 Claims. (Cl. 200-166) This invention relates toshorting devices and more particularly to a shorting device forsecondary terminals of current transformers.

In the transformer art and in particular in the field of instrumentcurrent transformers, dangerous electrical potentials may be developedacross the secondaries of such transformers, when energized, if no loadis connected to the secondary circuit. For this reason it is normalpractice to provide some type of shorting device to short circuit thesecondary terminals when the secondary circuit is disconnected,

Many types of shorting devices have been proposed. Most of the presentday shorting devices require some type of rotating member which may berotated between a shorting position and an open position with respect tosecondary terminals. While these prior art devices generally performtheir desired function they are essentially a complicated mechanicaldevice and are generally too costly for the type of equipment on whichthey are used. There has long been a need inthis field for a shortingdevice of a very simple and inexpensive construction. However, suchshorting device must necessarily provide a positive shorting positionbetween the terminals and must be readily moved and maintained in anon-shorting position.

Therefore it is one object of this invention to provide a simple,inexpensive shorting device.

A further object of this invention is to provide a one piece shortingdevice which may be readily moved in a linear direction from a shortingto an open position.

A still further object of this invention is to provide a one piece,inexpensive shorting device of resilient conducting material, whoseresiliency will maintain the device in a shorted or open position.

In carrying out this invention in one form a one-piece shorting deviceis provided made from resilient conducting material. The shorting deviceis provided with a central portion having a slotted opening therein forslidably engaging a member spaced between secondary terminals. Outwardlyextending arm members are provided on each side of the central portion,the arm members adapted to engage secondary terminals in one position ofthe shorting device. In the preferred embodiment, inwardly turned springarms are provided on the central portion and are adapted to engage themember between the secondary terminals when the shorting device is in asecond position.

The invention which it is desired to protect will be clearly pointed outand distinctly claimed in the claims appended hereto. However, it isbelieved that this invention and the manner in which its objects andadvantages are obtained, as well as other objects and advantagesthereof, will be more clearly understood by reference to the followingdetailed description thereof particularly when considered in the lightof the accompanying drawings, in which:

FIGURE 1 is a perspective view of a one piece shorting device accordingto the preferred embodiment of this invention;

FIGURE 2 is a top view of the shorting device of FIG. 1 showing suchdevice in shorted position between a pair of secondary terminals;

FIGURE 3 is a top view similar to FIG. 2 showing the shorting device inopen position; and

FIGURE 4 is a front view of the shorting device of FIG. 1 as appliedbetween secondary terminals.

Reference will now be made to the drawings in which like numerals areused to indicate like parts throughout the various views thereof for amore complete understanding of a preferred embodiment of the shorting device of this invention. Referring first to FIG. 1, there is shown aperspective view of a shorting device 10 made of a single piece ofresilient conducting material, such as for example copper. The shortingdevice 10 includes a central body portion 12 having a longitudinal slot14 extending substantially the length thereof. A pair of side members 16and 18 are provided forming the edges of slot 14. An upturned rearflange 20 is provided substantially connecting side members 16 and 18and lending resilient strength to body portion 12. A pair of shortingarms 22, 24 are provided connected to the forward portions of sides 16and 18 by the integral tabs 26 and 28, respectively, as shown. The arms22, 24 extend outwardly from each side of the central portion 12 and areprovided with bent portions 30, 32 which are adapted to engage secondaryterminals of a transformer as will more fully appear hereafter.

Also formed on the central body portion 12 are a pair of arm members 34,36 having inwardly turned tabs 38, 40 as shown. Each of tabs 38 and 40has an arcuately shaped end as is clearly evident from FIG. 1. The arms34 and 36 are integrally connected to the rear portion of sides 16 and18 in the manner shown and are adapted to engage a spaced member betweensecondary terminals as is more clearly apparent from FIGS. 2 through 4.

Referring now to FIG. 2 of the drawings, the shorting device 10 is shownas mounted on a spaced member 42 which is spaced between secondaryterminals 44 and 46 of a transformer. The spaced member 42 is providedwith slots on the side thereof as is indicated at 48 and 50. Sidemembers 16 and 18 engage the respective slots thereby slidably mountingshorting device 10 on spaced member 42. In the position shown in FIG. 2,the shorting device is slid into shorting position and bent members 30,32 of shorting arms 22, 24 engage the secondary terminals 44, 46 therebyshorting the secondary terminals and resiliently holding the shortingdevice in this shorted position.

FIGURE 3 shows shorting device 10 slid to the second position in whichtabs 38, 40-engage the spaced member 42 and shorting arms 22, 24 havemoved to the non-shorting or open position. As will be: clearly evidentfrom FIG. 3, the tabs 38, 40 on arms 34, 36, respectively, engage thespaced member 42 and resiliently hold shorting device 10 in the openposition.

FIGURE 4 of the drawings shows one method of mounting shorting device 10on the spaced member 42 between the terminals 44 and 46. Slottedportions 48, 50 on space member 42 are apparent in FIG. 4, slidablymounting the shorting device 10 on spaced member 42. Of course, as willbe understood in many types of instrument transformers the space member42 will be made of insulating material. However, if desired, as will beapparent, the spaced member 42 could be a third terminal denoting a tapon the secondary of the transformer. Obviously, were spaced member 42 athird secondary terminal, shorting device 10 when in the position shownin FIG. 2 would provide a shorting position between all of the secondaryterminals. It will be clear to those skilled in the art that terminals44 and 46 must have at least a portion thereof of conducting material sothat the shorting device when in the position shown in FIG. 2 willprovide a short circuit between terminals 44 and 46. In the preferredembodiment, the terminals 44 and 46 are in the form of brass studshaving openings 52 Patented Jan. 31, 1967 and 54, as shown in FIG. 4,for reception of secondary leads.

The shorting device of this invention is particularly useful with theterminal enclosure described and claimed in application Serial No.484,015 filed concurrently herewith in the name of Franklin R.DEntre'mont and assigned to the same assignee as this application. Whenused with the terminal enclosure of that application, the terminalenclosure may be provided with tabs which will engage the shortingdevice 10 moving such device to a shorted position when the terminalenclosure is placed on the secondary terminals in a position which doesnot allow access to the secondary terminals. When the enclosure isplaced on the secondary terminals to allow leads to extend therefrom,the enclosure may not be fully closed and sealed unless the shortingdevice is in the open circuit position shown in FIG. 3.

While there has been shown and described the present preferredembodiment of this invention, it will be obvious to those skilled in theart that various changes may be made in constructional details withoutdeparting from the spirit and scope of the invention as defined in theappended claims.

What is claimed as new and which it is desired to secure by LettersPatent of the United States is:

1. A one-piece shorting device for the secondary terminals of a currenttransformer having a member spaced between the secondary terminals, saidshorting device made from resilient conducting material comprising, acentral portion formed of a pair of side members, a slotted opening insaid central portion between said side members, said side membersadapted to slidably engage the spaced member between the secondaryterminals, arms formed on said central portion and extending outwardlytherefrom on each side thereof and having bent portion at theextremities thereof for engaging the secondary terminals when saidcentral portion is in one position on the spaced member, said centralportion being slidable on the spaced member to a second position inwhich said arms will be disengaged from the secondary terminals.

2. A one-piece shorting device formed from resilient conducting materialcomprising a central portion, a slotted opening in said central portionformed by side members which are adapted to slidably engage a spacedmember between secondary terminals, arms formed on said central portionand extending outwardly therefrom on each side thereof for engagingsecondary terminals when said central portion is in one position, saidcentral portion being movable to a second position in which said armsare adapted to be disengaged from secondary terminals, and a pair ofinwardly turned arms on said central portion, said pair of inwardlyturned arms adapted to engage the spaced member when said centralportion is in said second position.

3. A one-piece shorting device formed from resilient conducting materialcomprising a body portion, said body portion having a pair of sidemembers forming therebetween a slotted opening, a pair of shorting arms,each arm integrally connected to one of said side members and extendingoutwardly therefrom, said shorting arms being provided with bentportions at the extremities thereof, a second pair of arms integrallyconnected to said side members and having tab portions at theextremities thereof inwardly extending over said side members.

References Cited by the Examiner UNITED STATES PATENTS 2,721,243 10/1955Daily et al. 200--166 ROBERT K. SCHAEFER, Primary Examiner.

H. O. JONES, Assistant Examiner.

1. A ONE-PIECE SHORTING DEVICE FOR THE SECONDARY TERMINALS OF A CURRENTTRANSFORMER HAVING A MEMBER SPACED BETWEEN THE SECONDARY TERMINALS, SAIDSHORTING DEVICE MADE FROM RESILIENT CONDUCTING MATERIAL COMPRISING, ACENTRAL PORTION FORMED OF A PAIR OF SIDE MEMBERS, A SLOTTED OPENING INSAID CENTRAL PORTION BETWEEN SAID SIDE MEMBERS, SAID SIDE MEMBERSADAPTED TO SLIDABLY ENGAGE THE SPACED MEMBER BETWEEN THE SECONDARYTERMINALS, ARMS FORMED ON SAID CENTRAL PORTION AND EXTENDING OUTWARDLYTHEREFROM ON EACH SIDE THEREOF AND HAVING BENT PORTION AT THEEXTREMITIES THEREOF FOR ENGAGING THE SECONDARY TERMINALS WHEN SAIDCENTRAL PORTION IS IN ONE POSITION ON THE SPACED MEMBER, SAID CENTRALPORTION BEING SLIDABLE ON THE SPACED MEMBER TO A SECOND POSITION INWHICH SAID ARMS WILL BE DISENGAGED FROM THE SECONDARY TERMINALS.